I think Nvidia is more focused on PC, where AMD wants a piece of the console pie. I also wouldn't say Nvidia "couldn't" more like they wouldn't due to the questionable future of consoles. You never know the PS4 may flop. The casuals are taking over after all. Besides does Nvidia really need to rule over every hardware market? I don't think so.
You all are being Gearboxed I promise you! Man I can't believe so many are falling for Sony's tricks again. You people seriously forgot about the infamous Killzone "gameplay"? In game will look nothing like that.